The invention relates to a cathode ray tube comprising in an evacuated envelope an electron gun for directing an electron beam to a display screen. The electron gun comprises an electrostatic focusing lens, the electron beam being deflected during operation across said display screen in two mutually perpendicular directions, namely a line scan direction and a field scan direction.
A cathode ray tube of this type may be a projection television display tube or a different type of display tube in which only one electron beam is generated.
Phosphor saturation is a problem in projection tubes, particularly for the zinc sulfide phosphor used for blue. It is therefore desirable to provide a cathode ray tube with means to reduce the phosphor saturation.